Cutting material into lengths

ABSTRACT

Method and apparatus for cutting material into lengths, particularly for cutting tread rubber strips for tires, to maintain the length equal to or substantially equal to a predetermined value independent of any errors which may occur due to for example to mechanical lags, poor lubrication or general wear. Cut lengths are measured and the measured size compared with a predetermined value, and any required correction applied to the cutter automatically.

United States Patent 1 1 Sanders 51 May 15, 1973 v [54] CUTTING MATERIAL INTO LENGTHS [75] Inventor: Harry Sanders, Water Orton, Near Birmingham, England [73] Assignee: Dunlop Holdings Limited, London, 'England [22] Filed: May 7, 1970 [21] Appl.No.: 35,347

[30] Foreign Application Priority Data May 13, 1969 Great Britain ..24,209/69 [52] US. Cl. ..83/37, 83/73, 83/359, I 83/369, 83/522 [51] Int. Cl. ..B26d 5/40 [58] Field of Search ..83/73,74, 75, 76, 83/79, 358, 371, 37, 359, 369

[56] References Cited UNITED STATES PATENTS 3,324,751 6/1967 Rubinstein et a1 ..83/73 3,373,584 3/1968 Rondt et al. ..83/371 X 3,199,391 8/1965 Hauer et a1 ..83/359 FOREIGN PATENTS OR APPLICATIONS 704,165 2/1965 Canada ..83/359 Primary Examiner-Frank T. Y os t I Attorney-Stevens, Davis, Miller & Mosher [57] ABSTRACT Method and apparatus for cutting material into lengths, particularly for cutting tread rubber strips for tires, to maintain the length equal to or substantially equal to a predetermined value independent of any errors which may occur due to for example to mechanical lags, poor lubrication or general wear. Cut lengths are measured and the measured size compared with a predetermined value, and any required correction ap-' plied to the cutter automatically.

10 Claims, 1 Drawing Figure CUTTING MATERIAL INTO LENGTHS This invention relates to a method and apparatus for cutting material into lengths.

It is known to feed material on a conveyor past a measuring system to a cutter, and when a predetermined amount has been measured the cutter is automatically operated to cut a length from the material. It is found that the cut lengths are not of uniform size on account of, for example, lag in operation of the cutter due to poor lubrication or general wear. The incorrect size is often not discovered until many lengths have been cut and this can result in waste. Correction of the apparatus may have to be made manually, largely by trial anderror, and often several times in a given period, e.g. 1 day.

It is an object of the present invention to provide a method and apparatus for cutting lengths of material which are of substantially uniform size i.e. which substantially eliminates the aforementioned disadvantages.

According to the invention a method of cutting material into lengths each having a size substantially equal to a predetermined value comprises feeding the material past a cutting mechanism, operating the mechanism to sever a predetermined length of the material, sensing each end of a severed length with a sensing device to measure the size of the length severed, the device and length being relatively moveable, to detect any variation from the predetermined value, and supplying a signal proportional to any required correction to the cutting mechanism to adjust the operation of the cutting mechanism to obtain substantial uniformity of the size of a subsequently severed length with the predetermined value.

Preferably the sensing device is stationary and each severed length is fed past it.

According to a further aspect of the invention, apparatus for cutting material into lengths, each having a size substantially equal to a predetermined value, comprises a cutting mechanism operable at predetermined intervals, a conveyor for feeding the material past the cutting mechanism, a sensing device for sensing each end of a severed length to measure the size of the length cut, the sensing device and length being relatively moveable, means for detecting any variation in saidsize from said predetermined value and means for supplying a signal proportional to any required correction to the cutting mechanism to adjust the operation of the cutting mechanism to obtain substantial uniformity of thesize of a subsequently severed length with the predetermined value. Preferably the sensing device is stationary.

Preferably the cutting mechanism comprises a cutter and a first unit for measuring the length of uncut material which has been fed to the cutter, which unit is capable of actuating the cutter so as to sever a length having a size equal to or substantially equal to a predetermined size.

Preferably also the apparatus comprises a second measuring unit for measuring the size of a severed length being connected to the first unit and capable of sending any required correcting signal thereto before the next length is severed to obtain a subsequent length having a size equal to or substantially equal to the predetermined value.

One embodiment of the invention, an apparatus and method of cutting un-vulcanized tread rubber into substantially equal lengths, will now be described by way of example with reference to the accompanying diagrammatic drawing.

The apparatus comprises a conveyor belt 1 on which a continuous length of uncut tread rubber 2 is fed from an extruder (not shown), past a first measuring unit 3, then past a cutter 4 for cutting the tread rubber into lengths 5, and then past a second measuring unit 6. The first measuring unit 3 measures the length of uncut tread rubber 2 fed to the cutter 4 and the second measuring unit 6 measures the length of severed lengths 5.

as they are fed away from the cutter 4 on the belt 2.

The first measuring unit 3 comprises a knurled wheel 7 having a circumference of 1000 mm. mounted above the conveyor belt 2 for engagement with the top of the uncut tread rubber, and a pulse generator 8 driven through an axle 9 by the wheel 7 which generates a pulse for each millimeter of rotation of the wheel. These pulses are fed to and actuate a first presettable bi-directional counter 10 also forming part of the first measuring unit, the counter indicating on a first display 11, a preset count corresponding to the desired predetermined value of the severed length in millimeters and on a second display 12, a count corresponding to the length in millimeters of uncut tread rubber fed to the cutter.

The second measuring unit 6 comprises a knurled wheel 13, a pulse generator 14 and a bi-directional counter 15 each similar to corresponding first parts of the first measuring unit, but in this case the knurled wheel is mounted to engage the top side of the belt. The second unit further comprises a stationary sensing device comprising a light source (not shown) and a phototransistor 16, the latter being connected between the generator and the counter. The source and phototransistor 16 are positioned so that light from the source is interrupted by a severed length of tread rubber, and the phototransistor 16 is biassed to be conducting when under a dark condition and non-conducting when under a light condition. Thus pulses only pass from the generator to the counter when a severed length is passing the sensing device. The second counter 15 is also presettable and indicates on one display 17 the preset count corresponding to the desired predetermined value of the severed length in millimeters and on a second display 18 a count corresponding to the measured severed length in millimeters.

The bi-directional counters 10 and 15 and associated pulse generators 8 and 14 can detect forward or reverse movement of the knurled drive wheels 7 and 13 i.e. if

the wheel is driven in a forward direction the measured count will advance or increase, and if driven in a reverse direction will retard or decrease. This allows any of the forward or reverse movement detected in the tread rubber because of its inherent inertia and/or elasticity, especially during jerking conveyance, to be either deducted from or added to the count during operation of the measuring units. 1

The cutter 4 is of the known flying knife typehaving a knife cutter carriage (not shown), electropneumatically-operated clamping means (not shown) for clamping the carriage to the conveyor belt and a cutting knife 19 mounted on a traversing mechanism 20.

In operation both counters are first preset at a figure which represents the desired predetermined value of the severed length, and the extruded tread rubber 2 is fed on the conveyor belt 1 past the first measuring unit 3 and past the cutter 4 until the length of uncut tread rubber fed past the cutter equals the desired length i.e. the measured count equals the preset count. When this occurs a voltage output signal is obtained from the first counter 10 and after suitable amplification operates the cutter by effecting simultaneous clamping of the knife cutter carriage to the conveyor belt 1 and actuation of the cutting knife traversing mechanism.

Severed lengths of tread rubber are fed away from the cutter 4 past the second measuring unit 6. The counter 15 of the second unit is started as the leading edge of a severed value passes the sensing device phototransistor 16 and is stopped as the trailing edge passes. This counter 15 compares the measured count (i.e. measured length) with the preset count (i.e. desired predetermined value) and gives an output signal corresponding to the error involved should the length measured be outside a given tolerance range. This signal is fed back to the first measuring system counter and makes any required adjustment additively or subtractively to the preset count to obtain a predetermined size to which a subsequently severed length will be cut to have substantially the desired predetermined length. The counters also display the plus or minus error visually so that an operator may mark an out-of-tolerance length or take any other action.

As shown in the diagram the preset length displayed is 3000 mm. shown at display 17 on the second counter 15. This second counter also displays at display 18 the measured value of the last severed length to pass the sensing device phototransistor 16 and in the example shown is 2955 mm. The error is therefore 45 mm. and a corresponding error signal is passed to the first counter 10 and shown at display 11 as 3045 mm. i.e. the desired predetermined value plus the error.

As an alternative the output signal from the second counter may be used to operate an automatic reject device, an automatic marking device, an alarm device or a recording device recording the actual measurements made.

If the cutter is a stationary type instead of a flying knife, the conveyor belt 1 with the tread rubber 2 on it is braked to a halt on receipt ofa signal from the first counter 10, simultaneously with the operation of the cutting knife traverse mechanism. In either type of cutter there are inherent variables which are difficult to control and compensate for which affect the accuracy of the tread length cut. Examples of these variables are electro-mechanical-pneumatic delays, conveyor speed, air pressures, braking distances, machine wear and general lubrication and it is the effect of these that the present invention substantially overcomes.

It is a further advantage of the mechanism according to the invention that to change the desired predetermined length of cut rubber, the operator only has to preset the counter and not move the sensing device which could lead to the introduction of a further error.

Having now described my invention, what I claim is:

l. A method of cutting material into lengths each having a size substantially equal to a predetermined value comprising feeding the material past a cutting mechanism, measuring the length of material being fed past said cutting mechanism, operating the mechanism to sever the material which has moved past said cutting mechanism when the measured length is substantially equal to a predetermined length of the material, sens- .ing the distance between the two ends of a severed length of material with a sensing device to measure the actual size of the severed length, the device and length being relatively movable, comparing said actual size with a predetermined value to detect any variation from the predetermined value and supplying a signal proportional to any required correction to adjust the predetermined length against which the length of material being fed past the cutting mechanism is measured to adjust the operation of the cutting mechanism to eliminate any such variation and obtain substantial uniformity of the size of a subsequently severed length with the predetermined value.

2. A method according to claim 1 wherein the sensing device is stationary and the severed length is fed past it.

3. A method of cutting material into lengths according to claim 1 comprising the step of recording the measured size.

4. Apparatus for cutting material into lengths each having a size substantially equal to a predetermined value, comprising a cutting mechanism operable at predetermined intervals to sever a measured length of material, a conveyor for feeding the material past the cutting mechanism, a sensing device for sensing the distance between the two ends of a severed length of material to measure the actual size of the length cut, the sensing device and length being relatively movable, means for comparing said actual size with a predetermined value for detecting any variation in said size from said predetermined value and means for supplying a signal proportional to any required correction to adjust the predetermined length against which the length of material being fed past the cutting mechanism is measured to adjust the operation of the cutting mechanism to eliminate any such variation and obtain substantial uniformity of the size of a subsequently severed length with the predetermined value.

5. Apparatus according to claim 4 wherein the sensing device is stationary.

6. Apparatus for cutting material into lengths according to claim 4, wherein the cutting mechanism comprises a cutter and a first measuring unit for measuring the length of uncut material which has been fed to the cutter, said first measuring unit actuating the cutter when the measured length of uncut material reaches said predetermined length so as to sever a length having a size equal to or substantially equal to the predetermined length.

7. Apparatus for cutting material into lengths according to claim 6 wherein the first measuring unit comprises a knurled rotatable wheel engageable with uncut material being fed to the cutter, a pulse generator actuable by rotation of the wheel and a bi-directional counter connected to the pulse generator for counting the number of pulses received therefrom, the number of pulses being proportional to the length of uncut material fed to the cutter, the counter being capable of actuating the cutter when the number of pulses counted reaches said predetermined length.

8. Apparatus for cutting material into lengths according to claim 6, wherein said sensing device, said means for detecting variations in size and said means for supplying a signal are combined in a second measuring unit connected to said first measuring unit.

9. Apparatus according to claim 4 comprising a recording device 'for recording the sizes of severed lengths.

10. Apparatus for cutting material into lengths each having a size substantially equal to a predetermined value, comprising:

a cutting mechanism operable at predetermined intervals to sever a measured length of material;

a conveyor for feeding said material past said cutting mechanism;

a first measuring unit for measuring the length of uncut material which has been fed to the cutting mechanism, said first measuring unit actuating said cutting mechanism when the measured length of uncut material reaches a predetermined length; and

a second measuring unit coupled to said first measuring unit and including sensing means relatively movable with respect to the length of cut material for sensing the distance between the two ends of a severed length of material to measure the actual size of the length cut, means for detecting any variation in said size from said predetermined value,

means for supplying a signal proportional to any required correction to the cutting mechanism to adjust the operation of the cutting mechanism to obtain substantial uniformity of the size of a subsequently severed length with the predetermined value,

a knurled rotatable wheel engageable with the conveyor,

a pulse generator actuable by rotation of the wheel,

a bi-directional counter connected to the generator for counting the number of pulses received therefrom,

the sensing device actuating the counter only during the period when a severed length is sensed by the device whereby the count indicated by the counter is proportional to the size of the severed length, the bi-directional counter of the second measuring unit being capable of sending any required correcting signal to the counter of the first measuring unit to adjust the v predetermined count on the counter and therefore obtain a subsequent length having a size equal to or substantially equal to the predetermined value. 

1. A method of cutting material into lengths each having a size substantially equal to a predetermined value comprising feeding the material past a cutting mechanism, measuring the length of material being fed past said cutting mechanism, operating the mechanism to sever the material which has moved past said cutting mechanism when the measured length is substantially equal to a predetermined length of the material, sensing the distance between the two ends of a severed length of material with a sensing device to measure the actual size of the severed length, the device and length being relatively movable, comparing said actual size with a predetermined value to detect any variation from the predetermined value and supplying a signal proportional to any required correction to adjust the predetermined length against which the length of material being fed past the cutting mechanism is measured To adjust the operation of the cutting mechanism to eliminate any such variation and obtain substantial uniformity of the size of a subsequently severed length with the predetermined value.
 2. A method according to claim 1 wherein the sensing device is stationary and the severed length is fed past it.
 3. A method of cutting material into lengths according to claim 1 comprising the step of recording the measured size.
 4. Apparatus for cutting material into lengths each having a size substantially equal to a predetermined value, comprising a cutting mechanism operable at predetermined intervals to sever a measured length of material, a conveyor for feeding the material past the cutting mechanism, a sensing device for sensing the distance between the two ends of a severed length of material to measure the actual size of the length cut, the sensing device and length being relatively movable, means for comparing said actual size with a predetermined value for detecting any variation in said size from said predetermined value and means for supplying a signal proportional to any required correction to adjust the predetermined length against which the length of material being fed past the cutting mechanism is measured to adjust the operation of the cutting mechanism to eliminate any such variation and obtain substantial uniformity of the size of a subsequently severed length with the predetermined value.
 5. Apparatus according to claim 4 wherein the sensing device is stationary.
 6. Apparatus for cutting material into lengths according to claim 4, wherein the cutting mechanism comprises a cutter and a first measuring unit for measuring the length of uncut material which has been fed to the cutter, said first measuring unit actuating the cutter when the measured length of uncut material reaches said predetermined length so as to sever a length having a size equal to or substantially equal to the predetermined length.
 7. Apparatus for cutting material into lengths according to claim 6 wherein the first measuring unit comprises a knurled rotatable wheel engageable with uncut material being fed to the cutter, a pulse generator actuable by rotation of the wheel and a bi-directional counter connected to the pulse generator for counting the number of pulses received therefrom, the number of pulses being proportional to the length of uncut material fed to the cutter, the counter being capable of actuating the cutter when the number of pulses counted reaches said predetermined length.
 8. Apparatus for cutting material into lengths according to claim 6, wherein said sensing device, said means for detecting variations in size and said means for supplying a signal are combined in a second measuring unit connected to said first measuring unit.
 9. Apparatus according to claim 4 comprising a recording device for recording the sizes of severed lengths.
 10. Apparatus for cutting material into lengths each having a size substantially equal to a predetermined value, comprising: a cutting mechanism operable at predetermined intervals to sever a measured length of material; a conveyor for feeding said material past said cutting mechanism; a first measuring unit for measuring the length of uncut material which has been fed to the cutting mechanism, said first measuring unit actuating said cutting mechanism when the measured length of uncut material reaches a predetermined length; and a second measuring unit coupled to said first measuring unit and including sensing means relatively movable with respect to the length of cut material for sensing the distance between the two ends of a severed length of material to measure the actual size of the length cut, means for detecting any variation in said size from said predetermined value, means for supplying a signal proportional to any required correction to the cutting mechanism to adjust the operation of the cutting mechanism to obtain substantial uniformity of the size of a subsequently severed length with the predetermined value, a knurled rotatable wheel engageable with the conveyor, a pulse generator actuable by rotation of the wheel, a bi-directional counter connected to the generator for counting the number of pulses received therefrom, the sensing device actuating the counter only during the period when a severed length is sensed by the device whereby the count indicated by the counter is proportional to the size of the severed length, the bi-directional counter of the second measuring unit being capable of sending any required correcting signal to the counter of the first measuring unit to adjust the predetermined count on the counter and therefore obtain a subsequent length having a size equal to or substantially equal to the predetermined value. 